The present invention relates to a method and a device for contactless optical measurement of distance changes, in which a light beam is directed from a measuring table to an object at a defined distance and the scattered light produced on the surface of the object is directed by an optical system on the measuring table to a light sensor, and in the event of a change in the distance of the object relative to the measuring table the latter is displaced until such time as a scattered light maximum occurs on the light sensor, the distance of displacement of the measuring table corresponding to the distance change.
Devices of such a type have been known for a relatively long time, and have the advantage that the measurements are independent of the surface inclination of the object, since the scattered light is utilized for measurement purposes. However, it is a disadvantage that the scattered light maximum has a relatively weak intensity and can therefore only be evaluated with difficulty. This leads, in the final analysis, to measurement errors. Moreover, the scattered light maximum is difficult to locate, if extraneous light, more particularly scattered light of the same optical frequency, is present.